Regionalizing the City of Dayton's Lime Kiln Facility - Ohiowater.org

Lime Reclamation FacilityProcess Schematic

Sludge Production and LimeRecoveryLimeCaOSoftening ProcessRawWaterCaSludge =Lime AddedO.56Ca (removed) = SludgeCaCO 3 (sludge) x 0.56 = Lime as CaO

Lime / Sludge Balance30 MGD24 tpdLimeMTPClarifiersCa R = 156MTPFilters36 MGD26 tpdLimeOTPClarifiersCa R = 158To LRF 62 tpd SludgeOTPFiltersTo LRF 70 tpd Sludge

System LossesTotal PossibleSFBW LossCentrate LossNet SludgeNet Lime132 TPD Sludge10 TPD5 TPD117 TPD65 TPD

Tons/dayLime Production vs Usage120.00100.0080.0060.00Lime From Plant SludgeCombined Lime Usage40.00Multiplier = 1.2520.000.003/2/2012 3/7/2012 3/12/2012 3/17/2012 3/22/2012 3/27/2012 4/1/2012 4/6/2012 4/11/2012

PRODUCTION COSTFACTORS

Dayton Lime Production CostPower$8.46Maintenance $18.86TOTAL =$123.24Labor$53.81Gas$42.11

Dayton Sludge AlternativesWithout KilnCurrent annual costs(dollars)Sewer(dollars)Landfill(dollars)Maintenance 393,000 0 60,000Labor 1,180,000 0 570,000Fuel 921,967 0 0Power 190,000 0 75,000CO 2 0 119,000 119,000Lime (30,000) 2,514,850 2,514,850Disposal 9,809,375 2,646,250Net Cost 2,654,000 12,450,000 5,985,000

CFD MODELING

Baseline ModelPrimary AirFlow Rate: 7742.2 lb/hrTemperature: 65 o FComp.(vol%): O 2 : 20.62%N 2 : 77.78%H 2 O: 1.57%CO 2 : 0.03%Natural GasFlow Rate: 1459.9 lb/hrTemperature: 65 o FComp. (vol%): N 2 : 5.0%CH 4 : 80.0%C 2 H 6 : 15.0%System Pressure ~ 14.3 psi @ EL 750 ftNatural GasPrimary GasPreheated Secondary AirPreheated Secondary AirTemperature: 200.3 o FBack to KilnPreheated Secondary Air0Hot Lime ProductEstimated Heat Loss9.0 MBtu/hr in kilnCoolerKilnCold Lime ProductHot Lime ProductFlow Rate: 5708.3 lb/hrTemperature: 1546 o FComp. (wt%): CaO: 97.5%CaCO3 2.0%Inert: 0.5%Cold Secondary AirSlurry FeedFlow Rate: 15662.3 lb/hrTemperature: 90 o FComp. (wt%): Moisture: 32.00%CaCO 3 : 67.81%Inert: 0.29%Slurry FeedFlue Gas and Dust to expansion chamberDust Flow Rate: 574lb/hrComp. (wt%): CaCO 3 : 99.72%Inert: 0.28%Flue gas and dustTemperature: 373 o FFlue gas flow: 41958 lb/hrComp. (vol%) O 2 : 3.75%N 2 : 54.80%H 2 O: 29.42%CO2: 12.02%Estimated Heat Loss1.17 MBtu/hr in coolerCold Lime ProductFlow Rate: 5708.3 lb/hrTemperature: 150 o FComp. (wt%): CaO: 97.5%CaCO3 2.0%Inert: 0.5%Secondary AirFlow Rate: 23351 lb/hrTemperature: 65 o FComp.(vol%): O2: 20.62%N2: 77.78%H2O: 1.57%CO2: 0.03%Mass and energy balance seems reasonable, thus this set of inputs is usedfor CFD baseline simulation

Temperature Profiles

CaO Formation in the Kiln

DEMONSTRATIONTESTING

% CaCO3Calcium Purity of DeliveredSludge from Troy100.0%90.0%Mean = 92.9%80.0%70.0%60.0%50.0%

% CaCO3Calcium Purity of DeliveredSludge from Middletown100.0%90.0%80.0%Mean = 91.1%70.0%60.0%50.0%

Tons/daySources of Lime Production14012010080Avg Lime ProducedMean = 95.1604020Lime From ImportedSludgeMean = 35.6Lime From PlantSludgeMean = 59.503/2/2012 3/7/2012 3/12/2012 3/17/2012 3/22/2012 3/27/2012 4/1/2012 4/6/2012 4/11/2012

% CaCO3% Calcium Carbonate inCarbonation Tank Effluent100.00%90.00%80.00%% CaCO3 in CarbEff% CaCO3 in FracTank70.00%Carb Eff= 95.1%Frac Tank = 91.7%60.00%50.00%

% CaOLime Purity During Trial100.0%98.0%96.0%94.0%92.0%90.0%Op Test88.0%86.0%Average Purity = 97.9% CaO84.0%82.0%80.0%3/2/12 0:00 3/7/12 0:00 3/12/12 0:00 3/17/12 0:00 3/22/12 0:00 3/27/12 0:00 4/1/12 0:00 4/6/12 0:00 4/11/12 0:00 4/16/12 0:00

REGIONALIZATIONAPPROACH

Transport Sludge to LRF30 – 35%ParticipatingUtilitySludgeLagoon and/orDrying50 – 60%Buy Lime from LRF

Sludge Receiving and Blending

Regional Partner‣ Transport its sludge to Dayton LRF‣ Buys lime from Dayton LRF‣ Disposal costs eliminated – only transport‣ High quality lime < market value